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Current Fellows in the Radiation Epidemiology Branch

Meet the current fellows in the Radiation Epidemiology Branch and learn about research training opportunities.

Elizabeth (Lisa) Khaykin Cahoon, Ph.D., S.M., M.H.S. - Research Fellow

Elizabeth Khaykin

Elizabeth Khaykin Cahoon, Ph.D., S.M., M.H.S., joined the Radiation Epidemiology Branch (REB) as a postdoctoral fellow in July 2010. Dr. Cahoon received her master’s in biostatistics in 2005 and her Ph.D. in epidemiology in 2008, both from the Johns Hopkins Bloomberg School of Public Health. Her doctoral research involved examining patient safety in persons with serious mental illness. While at Johns Hopkins, Dr. Cahoon also conducted a meta-analysis on secondhand smoking and cancer for the U.S. Surgeon General’s report on The Health Consequences of Involuntary Exposure to Tobacco Smoke, contributed to writing of The International Agency for Research on Cancer, World Health Organization monograph on secondhand smoking and cancer, and researched the history of radon and cancer. Dr. Cahoon worked under the mentorship of Jonathan Samet, M.D., M.S., Department of Epidemiology Professor and Chair, Gail Daumit, M.D., M.H.S., Associate Professor of Medicine, and William Eaton, Ph.D., Department of Mental Health Professor and Chair during her time at Hopkins. In REB, Dr. Cahoon works with her primary mentor D. Michal Freedman, J.D., M.P.H., Ph.D., epidemiologist, evaluating cancer risks associated with medication use, ultraviolet radiation, and vitamin D in the United States Radiologic Technologists cohort. Dr. Cahoon also works with Kiyohiko Mabuchi, M.D., Dr.P.H., Deputy Chief of REB, head of the Chernobyl Research Unit, and senior scientist, and Alina V. Brenner, M.D., Ph.D., M.P.H., staff scientist on assessment of risks of thyroid cancer and related diseases in cohorts of persons exposed to radiation as a result of the Chernobyl accident.

DCEG Publications (text and abstracts from our publications database)

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Lienard Chang, B.S. – Postbaccalaureate Fellow

Lienard Chang joined the Radiation Epidemiology Branch (REB) as a postbaccalaureate fellow in December 2013. Mr. Chang obtained his B.S. in nuclear engineering at Pennsylvania State University in May 2013 and is currently an M.S. candidate in health physics at Georgetown University’s biomedical graduate education program. Throughout his education and work experience, Mr. Chang has worked on projects involving: power plant design recommendations in response to the Fukushima Daiichi accident; boron and xenon concentrations as functions of nuclear power cycle burn-up; liquid scintillation counting in research of nicotine receptors; and MARSSIM-based decommissioning. In REB, he is working primarily with Choonsik Lee, Ph.D., investigator, and Steve Simon, Ph.D., staff scientist, and is focusing on projects regarding external and medical dosimetry. One major project involves estimating organ doses for pediatric computational phantoms exposed to external photon radiation fields in the event of radiological accidents or attacks.

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Vana Derderian, B.S. - Postbaccalaureate Fellow

Vana Derderian joined the Radiation Epidemiology Branch (REB) in June 2014 as a postbaccalaureate fellow. She received a B.S. in public health science from the University of Maryland in 2012. Prior to joining REB, Ms. Derderian worked as an IRTA fellow at the NIH Clinical Center (CC) Department of Radiology and Imaging Sciences focusing on computed tomography (CT) radiation exposure extraction and monitoring, organ dose assessment, and developing quantitative tumor treatment response criteria in clinical trial patients.  Ms. Derderian is working under the mentorship of Choonsik Lee, Ph.D., investigator, REB, on various projects to optimize phantom-based computed tomography organ dose calculation and data extraction tools for the clinical setting, and with Amy Berrington de González, D. Phil., senior investigator, REB, on assessment of diagnostic computed tomography examination exposures for cancer risk in international pediatric and adult cohort studies.

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Cari Meinhold Kitahara, Ph.D. - Research Fellow

Cari Meinhold Kitahara, Ph.D., joined the Radiation Epidemiology Branch (REB) in 2008 as a predoctoral fellow to conduct her doctoral dissertation work on the etiology of thyroid cancer under the supervision of Amy Berrington de González, D.Phil., senior investigator, REB. In 2011, Dr. Kitahara received her Ph.D. in epidemiology from the Johns Hopkins Bloomberg School of Public Health after successfully defending her dissertation, entitled “The association of obesity with thyroid cancer risk and markers of thyroid function." Dr. Kitahara now works closely with Dr. Berrington de González and others in DCEG and DCCPS to investigate genetic and environmental factors influencing the risk of thyroid cancer and brain/central nervous system tumors and explore new methods for measuring and evaluating obesity and diet for cancer epidemiology studies. She is actively involved in several projects within the NCI Cohort Consortium, including facilitating the development of a large pooled study of the relationship between obesity and risk of thyroid and other rare cancers. Dr. Kitahara has a B.S. degree from the University of Michigan in biology and anthropology (2005) and an M.H.S. degree from the Johns Hopkins Bloomberg School of Public Health (2008).

DCEG Publications (text and abstracts from our publications database)

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Clara Kim Lam, M.P.H. - Predoctoral Fellow

Clara Kim

Clara Kim, M.P.H., is a predoctoral fellow in the Radiation Epidemiology Branch (REB) and is enrolled in the Ph.D. program in cancer epidemiology at the George Washington University School of Public Health and Health Services. Ms. Kim received a B.S. in biology and psychology from Brandeis University in 2005 and an M.P.H. in epidemiology from the George Washington University in 2009. For her M.P.H. final thesis she examined the significance of microRNA in the insulin pathway and the association with diabetes. Ms. Kim is working under the mentorship of Lindsay Morton, Ph.D., investigator, REB, to identify patterns of and risk factors for multiple primary cancers among patients with at least one hematologic malignancy.

DCEG Publications (text and abstracts from our publications database)

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Terrence Lee, Ph.D. - Postdoctoral Fellow

Terrence Lee

Terrence Lee, is a postdoctoral fellow in the Radiation Epidemiology Branch (REB). Dr. Lee successfully completed a Ph.D. program in occupational and environmental epidemiology at the Johns Hopkins Bloomberg School of Public Health in 2014. Mr. Lee received a B.S. in food biochemistry from the University of California at Davis in 1988 and an M.P.H. in epidemiology from the University of California at Los Angeles in 1990. He was also a postgraduate environmental health and industrial hygiene fellow at the Uniformed Service University for the Health Sciences in 1997. Mr. Lee served as a civilian epidemiologist with the U.S. Army for over 10 years; he also worked as a medical surveillance coordinator at the U.S. CDC in Beijing, China. Mr. Lee works with Mark Little, D.Phil., senior investigator, REB, and Alice Sigurdson, Ph.D., staff scientist, REB, on his doctoral dissertation which will use the U.S. Radiologic Technologist cohort to examine the risk factors for basal cell carcinoma and risk of subsequent cancer for those with basal cell carcinoma.

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Jason Liu, Sc.D., M.S.,  - Postdoctoral Fellow

Jason Liu, Sc.D., M.S., joined the Radiation Epidemiology Branch (REB) as a postdoctoral fellow in the summer of 2012.  Dr. Liu received a B.S. in cellular and molecular biology from the University of Michigan – Ann Arbor, an M.P.H. in epidemiology from Columbia University, and an M.S. in biostatistics and Sc.D. in epidemiology from Harvard University. For his doctoral thesis, he examined the influence of vitamin D and one-carbon metabolism factors on telomere length and endometrial cancer. In DCEG, he is working under the mentorship of Martha Linet, M.D., M.P.H., Chief of REB, and senior investigator, on the U.S. Radiologic Technologists Study to determine the role of occupational radiation exposure on cancer incidence and mortality.

DCEG Publications (text and abstracts from our publications database)

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Dayton McMillan, M.S.  - Postbaccalaureate Fellow

Dayton McMillan, M.S., joined the Radiation Epidemiology Branch (REB) as a postbaccalaureate fellow in June 2014. Mr. McMillan received a B.S. in environmental health and an M.S. in radiological health sciences from Colorado State University in May 2014. His M.S. thesis focused on evaluating the Cu-ATSM imaging agent for radiotherapy purposes. Mr. McMillan has also conducted additional research in areas of health and medical physics. Currently he works with Choonsik Lee, Ph.D., investigator, REB, on dose reconstruction research associated with medical imaging and radiotherapy applications. His current project entails comparison of simulated patient organ doses from modulated versus conventional computed tomography scans.

Estelle Ntowe, M.H.S. – Postbaccalaureate Fellow

Estelle Ntowe, M.H.S.,joined the Radiation Epidemiology Branch (REB) in October 2013 as a postbaccalaureate fellow. Ms. Ntowe earned her M.H.S in Environmental Health Sciences from the Johns Hopkins Bloomberg School of Public Health in 2013. She graduated from Penn State University with a bachelor’s degree in life sciences in 2009. Ms. Ntowe is working with Amy Berrington de González, D.Phil., senior investigator, REB, on radiation-induced cancers in an epidemiological cohort of radiologists and physicians performing fluoroscopically guided procedures. Ms. Ntowe also is conducting an analysis of radiotherapy modalities and second cancer risks in the Surveillance, Epidemiology, and End Results (SEER) Medicare database. In addition, she assists in projects assessing second cancer risk in the Kaiser Breast Cancer Survivors cohort.

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Anil Prasad Pyakuryal, Ph.D., M.S. - Postdoctoral Fellow

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Anil Prasad Pyakuryal, Ph.D., M.S., joined the Radiation Epidemiology Branch (REB) as a visiting fellow in April 2014. Dr. Pyakuryal earned an M.S. in electrical engineering from Southern Illinois University at Carbondale in 2002.  He received his Ph.D. in physics with a research concentration in radiation oncology physics from the Northwestern Memorial Hospital/University of Illinois at Chicago in 2011. His post-doctoral training focused on applying computational phantoms to understand radiation toxicity and secondary cancer after conventional and advanced radiation therapy.   Dr. Pyakuryal works under the mentorship of Choonsik Lee, Ph.D., investigator, REB, on projects related to organ dose reconstruction for radiotherapy patients. Their work includes a collaboration with the NIH Clinical Center.

Publications in PubMed

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Anna Romanyukha, M.S. – Predoctoral Fellow

Anna Romanyukha, M.S., is a predoctoral fellow in the Radiation Epidemiology Branch (REB). She received her Master of Science degree from the Georgetown University Health Physics program in December 2013, and her B.A. from the University of Maryland in May 2011. Ms. Romanyukha is working with Steven Simon, Ph.D., staff scientist, REB, and Andre Bouville, Ph.D., Scientist Emeritis, on the study of dietary patterns among Native Americans at the time of the Trinity nuclear test, as well as Trinity exposure maps. She is also working with Choonsik Lee, Ph.D., investigator, REB, on various projects dealing with computed tomography dose calculation tools. Previously she worked with Stephanie Lamart, Ph.D., REB, postdoctoral fellow, on measuring and quantifying uncertainties in human anatomy to be used in retrospective radiation dose reconstruction, as well as internal dose calculations using phantoms.

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